Near-field charging pad for wireless power charging of a receiver device that is temporarily unable to communicate

ABSTRACT

Disclosed is a system including RF circuitry configured to generate an RF signal; a plurality of unit cells configured to receive the RF signal and to cause an RF energy signal having a center frequency to be present within the unit cells; and receiver circuitry configured to charge an electronic device in response to an antenna of the electronic device receiving the RF energy signal when the antenna is tuned to the center frequency and positioned in a near-field distance from one or more of the unit cells.

CROSS-REFERENCE TO RELATED APPLICATIONS

This non-provisional patent application claims the benefit of U.S.Provisional Patent Application Ser. No. 62/387,205, entitled “Near FieldTransmitters for Wireless Power Charging,” filed Dec. 24, 2015, which isincorporated by reference herein in it is entirety.

TECHNICAL FIELD

Generally, the present disclosure relates to wireless charging. Moreparticularly, the present disclosure relates to low-power near fieldcharging surfaces.

BACKGROUND

Electronic devices, such as laptop computers, smartphones, portablegaming devices, tablets, or others, require power to operate. Asgenerally understood, electronic equipment is often charged at leastonce a day, or in high-use or power-hungry electronic devices, more thanonce a day. Such activity may be tedious and may present a burden tosome users. For example, a user may be required to carry chargers incase his electronic equipment is lacking power. In addition, some usershave to find available power sources to connect to, which is timeconsuming. Lastly, some users must plug into a wall or some other powersupply to be able to charge their electronic device. However, suchactivity may render electronic devices inoperable or not portable duringcharging.

Some conventional solutions include an inductive charging pad, which mayemploy magnetic induction or resonating coils. As understood in the art,such a solution still requires the electronic devices to: (i) be placedin a specific location on the inductive charging pad, and (ii) beparticularly oriented for powering due to electromagnetic fields havinga particular orientation. Furthermore, inductive charging units requirelarge coils in both devices (i.e., the charger and the device beingcharged by the charger), which may not desirable due to size and cost,for example. Therefore, electronic devices may not sufficiently chargeor may not receive a charge if not oriented properly on the inductivecharging pad. And, users can be frustrated when an electronic device isnot charged as expected after using a charging mat, thereby destroyingthe credibility of the charging mat.

Other conventional solutions use far field RF wave transmission tocreate pockets of energy at remote locations for charging a device. Suchsolutions, however, are better suited for particular uses andconfigurations as far field RF wave transmission solutions typically usenumerous antenna arrays and circuitry for providing phase and amplitudecontrol of the RF waves. Accordingly, there is a desire for aneconomical application of a charging surface that allows for low-power,wireless charging without requiring a particular orientation forproviding a sufficient charge.

SUMMARY

In one embodiment, the present disclosure provides a method for chargingan electronic device, the method comprising applying an RF signal to acharging surface having a plurality of unit cells to cause an RF energysignal to be present within the unit cells of the charging surface forcharging the electronic device in response to an antenna of theelectronic device being positioned in a near-field distance from atleast one of the unit cells. The unit cells may at least in part be aperiodic structure, where the periodic structure may be locally periodicwhile being adaptive as function of location within the structure.

In one embodiment, the present disclosure provides a charging surfacedevice comprising: circuitry configured to generate an RF signal; and aplurality of unit cells configured to receive the RF signal and cause anRF energy signal to be present for charging an electronic device inresponse to an antenna of the electronic device being positioned in anear-field distance measured from a surface of at least one of the unitcells.

In one embodiment, the present disclosure provides a method for chargingan electronic device, the method comprising: applying an RF signal to aplurality of unit cells of a charging surface to cause an RF energysignal to be present within the unit cells of the charging surface;receiving the RF energy signal at an antenna of a wireless device whenthe antenna is positioned in a near-field distance from at least one ofthe unit cells; and charging a battery of the electronic device inresponse to the antenna receiving the RF energy signal.

In one embodiment, the present disclosure provides a system comprising:RF circuitry configured to generate an RF signal; an adaptive couplingsurface (here, a charging surface) comprising a plurality of unit cellsconfigured to receive the RF signal and to cause an RF energy signal tobe trapped/stored within the unit cells when the receiver device is notpresent and to leak the energy when the receiver is within a near-fieldregion of the surface. Receiver circuitry of an electronic device to becharged may be configured to charge the electronic device in response toan antenna of the electronic device receiving the RF energy signal whenthe antenna is positioned in a near-field distance from one or more ofthe unit cells (of the coupling surface).

In one embodiment, the present disclosure provides a method for chargingan electronic device, the method comprising: generating an RF signal;applying the RF signal, by a conductive line extending through a via, toa patch antenna member of a unit cell (i.e., located within the couplingsurface, where the patent antenna member or exciting element may be apart of the coupling surface design (e.g., one of the unit cells) or theexciting element may be an additional element placed within the otherunit cells); generating, by the patch antenna, an RF energy signal inthe unit cell; and leaking the RF energy signal from the unit cell to anantenna of the electronic device when the antenna is positioned in anear-field distance from the unit cell.

In one embodiment, the present disclosure provides a charging surfacedevice comprising: a plurality of unit cells configured to receive oneor more RF signals, each unit cell including: a patch antenna configuredto: (i) receive one of the one or more RF signals, and (ii) generate anRF energy signal for charging an electronic device, and an apertureconfigured to leak the RF energy signal from the unit cell when anantenna of the electronic device is positioned in a near-field distancefrom the unit cell.

In one embodiment, the present disclosure provides a method for charginga device, the method comprising: applying an RF signal to a plurality ofunit cells of a charging surface to cause an RF energy signal to bepresent within the unit cells of the charging surface; and filtering theRF energy signal using a harmonic screen filter element to produce theRF energy signal for charging the electronic device in response to anantenna of the electronic device being positioned in a near-fielddistance from at least one of the unit cells.

In one embodiment, the present disclosure provides a charging surfacedevice comprising: circuitry configured to generate an RF signal; aplurality of unit cells configured to receive the RF signal and to causean RF energy signal to be present within one or more of the unit cells;and a harmonic screen filter element configured to filter the RF energysignal for charging the electronic device in response to an antenna ofthe electronic device being positioned in a near-field distance from atleast one of the unit cells.

In one embodiment, the present disclosure provides a method ofmanufacturing a charging surface device, the method comprising: couplingcircuitry configured to generate an RF signal to a plurality of unitcells, the plurality of unit cells configured to receive the RF signaland to cause an RF energy signal to be present within one or more of theunit cells; and attaching a harmonic screen filter element configured tofilter the RF energy signal for charging the electronic device inresponse to an antenna of the electronic device being positioned in anear-field distance from at least one of the unit cells.

In one embodiment, the present disclosure provides a method for chargingan electronic device, the method comprising: receiving, by an antennaconfigured with a bandwidth that includes a center frequency and used tocommunicate wireless signals, a wireless charging signal operating atthe center frequency, the wireless charging signal received from acharging surface positioned in a near-field distance from the antenna;and responsive to determining that the antenna is receiving a powerabove a threshold level, routing the received wireless charging signalto a rectifier to convert the wireless charging signal to a powersignal.

In one embodiment, the present disclosure provides a system comprising:receiver circuitry configured to determine a power from a wirelesscharging signal received by an antenna used to communicate wirelesssignals, the wireless charging signal received by the antenna from acharging surface positioned in a near-field distance from the antenna;comparator circuitry configured to compare the power to a thresholdlevel; rectifier circuitry configured to rectify the received wirelesscharging signal to produce a rectified signal; a voltage converterconfigured to convert the rectified signal to a voltage to charge achargeable battery; and switching circuitry configured to route thereceived wireless charging signal to the rectifier when the powerexceeds the threshold level.

In one embodiment, the present disclosure provides a method for chargingan electronic device, the method comprising: receiving a signalindicative of a request for charging the electronic device; generating,in response to receiving the signal, an RF signal; applying the RFsignal to a plurality of unit cells of a charging surface to cause an RFenergy signal to be present in the unit cells of the charging surfacefor charging the electronic device; and leaking the RF energy signalfrom the unit cells of the charging surface to an antenna of theelectronic device when the antenna is positioned in a near-fielddistance to at least one of the unit cells.

In one embodiment, the present disclosure provides a charging surfacedevice comprising: control circuitry configured to receive a signalindicative of a request for charging an electronic device; a pluralityof patch antennas each configured to generate an RF energy signal; and aplurality of unit cells configured to leak the RF energy signal from theunit cells when an antenna of the electronic device is tuned to thecenter frequency and positioned in a near-field distance from at leastone of the unit cells.

In one embodiment, the present disclosure provides a method for chargingan electronic device, the method comprising: producing a low-power RFenergy signal in a unit cell of a charging surface; leaking thelow-power RF energy signal from the unit cell of the charging surface toan antenna of the electronic device when the antenna is positioned in anear-field distance from the unit cell; sensing the low-power RF energysignal in the unit cell of the charging surface; comparing the low-powerRF energy signal in the unit cell of the charging surface to a thresholdlevel; and producing, if the low-power RF energy signal is below thethreshold level, a subsequent low-power RF energy signal in the unitcell of the charging surface.

In one embodiment, the present disclosure provides a charging surfacedevice comprising: a feeding element, such as a patch antenna, may beconfigured to produce a low-power RF energy signal; a unit cellinclusive of the feeding element, here the patch antenna, the unit cellconfigured to retain the low-power RF energy signal when an antenna ofan electronic device is not positioned in a near-field distance from theunit cell, and configured to leak the low-power RF energy signal whenthe antenna of the electronic device is positioned in the near-fielddistance from the unit cell; and control circuitry configured to sensethe low-power RF energy signal in the unit cell, compare the low-powerRF energy signal to a threshold, and to cause, if the low-power RFenergy signal is below the threshold, the patch antenna to produce asubsequent low-power RF energy signal stored in the unit cell.

In one embodiment, the present disclosure provides a method for chargingan electronic device, the method comprising: leaking an RF energy signalfrom a charging surface in response to a metal structure beingproximately positioned at a surface of the charging surface to cause theRF energy signal to enter a space formed between the surface of thecharging surface and the metal structure so that an antenna of theelectronic device can receive the leaked RF energy signal and route thereceived RF energy signal to a rectifier to convert the RF energy signalto charge a chargeable battery.

In one embodiment, the present disclosure provides a method for chargingan electronic device, the method comprising: applying an RF signal to aplurality of unit cells of a charging surface to cause an RF energysignal to be present within the unit cells of the charging surface; andleaking the RF energy signal from one or more of the unit cells to a gapformed between a surface of the charging surface and a metal portion ofthe electronic device positioned in a near-field distance from the oneor more of the unit cells to cause an antenna of the electronic deviceto receive the RF energy signal for charging the electronic device.

In one embodiment, the present disclosure provides a charging surfacedevice comprising: circuitry configured to generate an RF signal; and aplurality of unit cells configured to receive the RF signal and to causean RF energy signal to be present in the unit cells for charging anelectronic device positioned in a near-field distance from one or moreof the unit cells by leaking the RF energy signal from the one or moreof the unit cells to a cavity/gap formed between a surface of thecharging surface and a metal portion of the electronic device to causean antenna of the electronic device to receive the RF energy signal forcharging the electronic device.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present disclosure are described by way of examplewith reference to the accompanying figures, which are schematic and maynot be drawn to scale. Unless indicated as representing prior art, thefigures represent aspects of the present disclosure.

FIG. 1A is an illustration of an example embodiment of an electronicdevice positioned on an illustrative charging surface that produces anRF energy signal for charging the electronic device, in accordance withan embodiment of the present disclosure;

FIG. 1B is an illustrative table having a charging surface on which anelectronic device is positioned.

FIG. 2A is a schematic diagram of an illustrative charging surface forgenerating RF energy signals to charge an electronic device, inaccordance with an embodiment the present disclosure;

FIG. 2B is a flow diagram illustrating operation of the illustrativecharging surface in accordance with one or more embodiments of thepresent disclosure;

FIG. 2C is a flow diagram illustrating a more detailed operation of theillustrative charging surface in accordance with one or more embodimentsof the present disclosure;

FIG. 3A is a schematic diagram of an illustrative electronic device forreceiving the RF energy signals generated by a charging surface, inaccordance with an embodiment of the present disclosure;

FIG. 3B is a flow diagram illustrating operation of the illustrativeelectronic device in accordance with one or more embodiments of thepresent disclosure;

FIG. 4A is an illustrative schematic diagram of circuitry representingthe charging surface when no electronic device is positioned within thenear-field distance;

FIG. 4B is an illustrative schematic diagram of circuitry representingthe charging surface when an electronic device is positioned within thenear-field distance;

FIG. 4C shows schematic models of equivalent circuits with two states ofenergy flow without and with an electronic device positioned in anear-field distance of the charging surface;

FIG. 4D is an illustration of an alternative representation of theschematic models of FIG. 4C;

FIG. 5A is an illustration of a top-side view of an example embodimentof an antenna portion of a charging surface including two substratelayers, in accordance with an embodiment of the present disclosure;

FIG. 5B is a bottom-side view of an example embodiment of a feedingportion (i.e. slot being made into the ground plane of the surface) of acharging surface including two substrate layers, in accordance with anembodiment of the present disclosure;

FIG. 5C is a perspective view of an example embodiment of a unit cellused for the antenna portion of the charging surface illustrated inFIGS. 5A and 5B, in accordance with an embodiment of the presentdisclosure;

FIG. 5D is an overhead view of the example embodiment of the unit cellillustrated in FIG. 5C, in accordance with an embodiment of the presentdisclosure;

FIG. 6A is a top-side view of an example embodiment of an antennaportion of a charging surface formed with one substrate layer, inaccordance with an embodiment of the present disclosure;

FIG. 6B illustrates a bottom-side view of an example embodiment of anantenna portion of a charging surface formed with one substrate layer,in accordance with an embodiment of the present disclosure;

FIG. 6C illustrates a perspective view of an example embodiment of aunit cell including a portion of the antenna portion of the chargingsurface illustrated in FIGS. 6A and 6B, in accordance with an embodimentof the present disclosure;

FIG. 6D illustrates an overhead view of the example embodiment of theunit cell illustrated in FIG. 6C, in accordance with an embodiment ofthe present disclosure;

FIG. 6E is an illustration of a cross-sectional view of an illustrativecharging surface inclusive of a plurality of unit cells;

FIG. 7A illustrates a cross-sectional view of an example embodiment ofan electronic device positioned within a near-field distance from acharging surface, in accordance with an embodiment of the presentdisclosure;

FIG. 7B illustrates an illustrative electronic schematic of theelectronic device of FIG. 7A;

FIG. 8A illustrates resonance of an example RF energy signal locatedbetween an electronic device with metallic surface and a surface of acharging device, in accordance with an embodiment of the presentdisclosure;

FIGS. 8B-8D illustrate a more detailed schematic of a charging surfacethat provides for a resonant-coupler to charge an electronic device, inaccordance with an embodiment of the present disclosure;

FIG. 9 illustrates a flow diagram of an example method for charging anelectronic device using a charging surface, where the electronic devicecommunicates a signal indicative of a request to charge or otherwisepairs with the charging surface, in accordance with an embodiment of thepresent disclosure;

FIG. 10 illustrates a flow diagram of an example method for charging anelectronic device using a charging surface when the electronic devicedoes not communicate a signal indicative of a request to charge, inaccordance with an embodiment of the present disclosure;

FIG. 11A illustrates a perspective view of an embodiment of a unit cellof a charging surface having a harmonic screen filter element, where theharmonic screen filter element is positioned on or above a top surfaceof the unit cell;

FIG. 11B illustrates a cross-sectional view of an embodiment of a unitcell of a charging surface having a harmonic screen filter element(note, the harmonic filter screen may also be made of periodic unitcells), where the harmonic screen filter element is positioned on orabove a top surface of the unit cell;

FIG. 12A illustrates a perspective view of an embodiment of a unit cellof a charging surface having a harmonic screen filter element, where theharmonic screen filter element is positioned within a substrate layer ofthe unit cell; and

FIG. 12B illustrates a cross-sectional view of an embodiment of a unitcell of a charging surface having a harmonic screen filter element,where the harmonic screen filter element is positioned within asubstrate layer of the unit cell.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. In the drawings, whichmay not be to scale or to proportion, similar symbols typically identifysimilar components, unless context dictates otherwise. The illustrativeembodiments described in the detailed description, drawings and claimsare not meant to be limiting. Other embodiments may be used and/or andother changes may be made without departing from the spirit or scope ofthe present disclosure.

Wireless Charging & High-Impedance Surfaces

FIG. 1A illustrates an embodiment of the present disclosure related to acharging surface, where an exemplary electronic device 104 is positionedon an illustrative charging surface 102 that produces a radio frequency(RF) energy signal for charging the electronic device 104. The chargingsurface 102 is shown as a pad, but it should be understood that thecharging surface 102 may have any configuration, such as a desktopsurface or portion thereof, housing of another electronic ornon-electronic device, or any other surface in which RF charging vianear-field RF signals may be provided to charge or power an electronicdevice, as described herein. The charging surface 102 may generate oneor more RF energy signals for wireless power transmission that arereceived by the electronic device 104 when the electronic device 104,and more specifically, an antenna of the electronic device 104, ispositioned within a near-field distance (e.g., preferably less thanapproximately 4 mm) from the charging surface 102. Alternativenear-field distances, both higher than 4 mm and lower than 4 mmdepending on the application and configuration of the charging surface102, may be utilized. The received RF energy signals are then convertedto a power signal by a power conversion circuit (e.g., rectifiercircuit) (not shown) for charging a battery of the electronic device104. In some embodiments, the total power output by the charging surface102 is less than or equal to 1 Watt to conform to Federal CommunicationsCommission (FCC) regulations part 15 (low-power, non-licensedtransmitters).

In some embodiments, the electronic device 104 may include anyelectronic device including the RF power converter components describedherein. For example, the electronic device may be any of a variety ofportable technologies, such as a tablet, laptop, cell phone, PDA,wearable device, such as smart watches, fitness devices, headsets, orany other portable, mobile, or other electronic device technology thatis capable of being recharged or operated utilizing the principlesdescribed herein.

In some embodiments, a charging surface 102 may include a housingdefined by a plurality of sidewalls 106, a top surface 108, and a bottomsurface (not shown). The top surface 108 extends over the bottomsurface. The sidewalls 106 span between the top surface 108 and thebottom surface. In some embodiments, the housing is formed of plastic,but alternatively or additionally can be formed of other material(s),such as wood, metal, rubber, glass, or other material that is capable ofproviding for the functionality described herein. As illustrated in FIG.1A, the charging surface 102 has a shape of a cuboid, but othertwo-dimensional or three-dimensional shapes are possible, such as acube, a sphere, a hemisphere, a dome, a cone, a pyramid, or any otherpolygonal or non-polygonal shape, whether having an open-shape or aclosed-shape. In some embodiments, the housing is waterproof orwater-resistant. The charging surface 102 may be stiff or flexible andoptionally include a non-skid bottom surface to resist movement whenplaced on a desktop or tabletop. Similarly, the top surface 108 may beor include non-skid region(s) (e.g., strips) (not shown) or be entirelynon-skid to resist motion between the surface 108 and an electronicdevice. Still yet, a bracket or other guide may be mounted to the topsurface 108 to assist a user with positioning of an electronic device.The housing may contain various components of the charging surface 102,which are described in greater detail herein. Note, the charging surfacemay be made of heat-conductive material (e.g., aluminum nitride) toabsorb heat from the receiver device. Moreover, the entire couplingsurface may be made of high-DK (i.e., with high dielectric permittivity)plastics/ceramics that may also be used to mold the unit cells to formthe surface.

As described in greater detail below, the charging surface 102 mayinclude a plurality of unit cell antennas formed, at least partially,from a substrate material. The substrate may include a metamaterial(i.e., an artificial material being made using small, compared to awavelength of a signal being transmitted, elements such as patches,dipoles or slots), such as FR4, Rogers, ceramic, or any other materialknown in the art. The unit cells are designed to retain the RF energysignal used to charge the electronic device 104 prior to the electronicdevice 104 being placed on the charging surface 102. That is, when thereis no antenna of the electronic device 104 positioned within thenear-field distance, or an antenna of the electronic device 104 is nottuned or otherwise configured to receive the RF energy signal, the unitcells do not leak or have minimal leakage of the RF energy signal.However, the unit cells are adaptably configured to allow the RF energysignal to leak from the unit cells to an antenna of the electronicdevice 104 when the antenna is positioned within the near-field distancefrom the unit cell, and is tuned to the frequency of the RF energysignal (or is otherwise configured to receive the RF energy signal). Inthe present disclosure, one embodiment of an antenna is considered“tuned” to a particular frequency when leakage of an RF energy signalfrom the charging surface 102 with metamaterial occurs. One or moresurfaces of the unit cell may be formed using metamaterial. For example,a ground plane, antenna patch, and/or both may be formed of metamaterialdepending on design criteria.

In configuring the unit cells of the charging surface 102, the unitcells may be periodically spaced and sized such that a frequency signalthat is generated and propagating within a substrate of the unit cellsmay be substantially retained within the charging surface 102 prior tothe electronic device 104 being placed within the near-field of thecharging surface 102. That is, when an antenna of the electronic device104 is place in the near-field of the charging surface 102, a change inthe boundary conditions of the charging surface results due tocapacitance and inductance electrical characteristics being introducedby the electronic device at the surface of the unit cells (see FIGS. 4Aand 4B).

The surface may be designed so that electromagnetic tuning results toenable leakage at the particular unit cell(s) that are within thenear-field distance of the antenna(s) of the charging surface 102. When“tuned” properly, an RF energy signal is retained within a substrate ofthe unit cells of the charging surface 102 and no or minimal leakageoccurs. The RF energy signal, when no antenna is in the near-field ofthe charging surface 102, reflects from the surface of the chargingsurface 102, such that no or minimal leakage occurs. And, when “tuned”properly, as when an antenna of the electronic device 104 is within thenear-field of the charging surface 102, the surface characteristics ofthe charging surface 102 change and the signals may become aligned withslot dipoles or other feature of the unit cell(s) at the location of theantenna of the electronic device 104 to cause leakage to occur at thatlocation. In the event that a different frequency is to be used, adimensional change may be made to the unit cells of the charging surface102 to accommodate the different frequency to avoid leakage. As anexample, if higher frequencies are used, smaller unit cells need to beincluded to provide similar performance.

With regard to FIG. 1B, an illustration of an illustrative table 110inclusive of a surface 112 on which an electronic device 114 ispositioned is shown. The surface 112 may fully or partially beconfigured to operate as a charging surface utilizing the same orsimilar principles and configuration as the charging surface 102. Byproviding a piece of furniture, for example, inclusive of a chargingsurface, the electronic device 114 may be placed on the charging surface112 and the electronic device 114 will charge independent of a separatecharging device or external pad, such as shown in FIG. 1A. It should beunderstood that a wide variety of devices, furniture, and/or structuresmay be configured to include a charging surface on one or more surfaceregions of the devices, furniture, and/or structures. It should also beunderstood that while a horizontal surface is desirable, alternativeangled surfaces may be provided, as well.

As shown, an antenna layer 116 provides for the same or similarstructure as the charging surface 102 such that an RF energy signal maybe leaked from the charging surface 102 in response to an antenna tunedto the frequency of the RF energy signal being positioned in anear-field distance of the charging surface 102. In one embodiment,rather than the entire charging surface 112 being configured tooperatively charge an electronic device, a portion of the chargingsurface 112 may be configured to perform the charging functionality, asdescribed herein.

FIG. 2A illustrates a schematic diagram 200 of various componentsincluding an embodiment of the charging surface 102 of FIG. 1A. Thecharging surface 102 may include a housing 202, where antenna elements204 (shown as antenna elements 204 a through 204 n), digital signalprocessor (DSP) or microcontroller 208, and optional communicationscomponent 210 may be included. Housing 202 can be made of any suitablematerial, for example plastic or hard rubber, that allows for signal orwave transmission and/or reception. Antenna elements 204 are eachdisposed within one of the unit cells of the charging surface 102, andmay include suitable antenna types for operating in frequency bands suchas 900 MHz, 2.5 GHz, or 5.8 GHz as these frequency bands conform toFederal Communications Commission (FCC) regulations part 18 (Industrial,Scientific and Medical (ISM) equipment). Other frequencies and multiplefrequencies are also possible. Suitable antenna types may include, forexample, patch antennas with heights from about 1/24 inch to about 1inch and widths from about 1/24 inch to about 1 inch. Other types ofantenna elements 204 may be used, for example, metamaterials and dipoleantennas, among others.

In one embodiment, a microcontroller 208 may include circuitry forgenerating and controlling RF transmission using antenna elements 204.These RF signals may be produced using an external power supply 212 andRF circuitry (not shown) including a local oscillator chip (not shown)using a suitable piezoelectric material, filters, and other components.These RF signals are then connected to the antennas 204 and cause an RFenergy signal to be present in the unit cells of the charging surface102. Microcontroller 208 may also process information sent by a receiverthrough its own antenna elements for determining times for generatingthe RF signals and for causing the appropriate power level to beproduced by the resulting RF energy signals. In some embodiments, thismay be achieved using communications component 210 configured to causethe RF energy signals to be produced within a desired frequency range,as previously described and as understood in the art. In an alternativeconfiguration, rather than using a local signal generator, a non-localsignal generator (i.e., outside the charging surface 102) may beutilized.

In some embodiments, a power amplifier (not shown) and gain controlcircuitry (not shown) may be applied to each antenna 204. However, giventhe number of antennas that may be used in a charging surface 102, theuse of one or more power amplifiers amplify an RF signal (an RF signalthat is supplied to or generated within the charging surface 102) inorder to generate an RF energy signal (the signal that is applied to theantennas 204) to feed each of the multiple antennas 204 provides forreduced circuitry and lower cost. In one specific embodiment, four RFinput ports (not shown) may be used to feed the antennas 204 of thecharging surface 102. In designing the charging surface 102, a single RFinput port or RF generator internal to the charging surface 102 maysupport a certain number or ratio of antennas 204.

In one embodiment, communications component 210 may include a standardwireless communication protocol, such as Bluetooth® or ZigBee®. Inaddition, communications component 210 may be used to transfer otherdata, such as an identifier for the electronic device 104 or surface102, battery level, location, charge data, or other such data. Othercommunications components may be possible, which may include radar,infrared cameras, or frequency-sensing devices for sonic triangulationto determine the position of the electronic device 104.

In one embodiment, in response to the communications component receivinga wireless signal (e.g., Bluetooth® signal) from an electronic device tobe charged by the charging surface 102, the microcontroller 208 may benotified using a digital signal 214 to responsively cause thecommunications component 210 to generate an RF energy signal 216 to beapplied to antennas 204. In an alternative embodiment, thecommunications component may have its own RF circuitry and antenna(s)for receiving wireless signals, and the microcontroller causes RF energyfor charging to be applied to the antennas. With such a configuration,an RF port (see FIGS. 5B and 6B) may provide for an electrical conductorto provide for an RF signal to be communicated to the communicationscomponent 210 for processing and communication to the antennas 204. Inyet another embodiment, a separate device, such as battery pack,protection case of a mobile device, or any other device that may be usedto charge or power an electronic device may include RF circuitry andantenna(s) for receiving wireless signals from the charging surface 102.

In one embodiment, a separate antenna (not shown) may be configured toreceive RF signals and communicate the received RF signals to thecommunications component 210 for processing and/or directly routing tothe antennas 204. The use of a separate antenna may enable the chargingsurface 102 to be operated remotely from a far-field transmitter thattransmits an RF charging signal to the charging surface 102 for chargingor powering an electronic device in a near-field manner, as describedherein.

The power supply 212 may be provided by way of a connection (e.g., a USBor microUSB connection) to a laptop, wall charger, internal battery,external battery, or other power source. The power supply 212 may beused to power circuitry on or at the charging surface 102.

FIG. 2B is a flow diagram 250 illustrating general operation of thecharging surface 102 in accordance with one or more embodiments of thepresent disclosure. At step 252, the charging surface 102 generates anRF energy signal in one or more of the unit cells of the chargingsurface 102. The unit cells retain substantially all (e.g., below acertain leakage threshold, such as −30 dB below the RF energy signal) ofthe RF energy signal used to charge the electronic device 104 when thereis no electronic device 104 antenna positioned within a near-fielddistance from any of the antennas 204 of the unit cells or if theantenna of the electronic device 104 is not tuned or otherwiseconfigured to receive the RF energy signal. At step 254, the unit cellsadapt to allow the RF energy signal to leak from the unit cells to anantenna of the electronic device 104 when the antenna is: (i) positionedwithin the near-field distance from one of the unit cell antennas 204,and (ii) tuned to the frequency of the RF energy signal (or is otherwiseconfigured to receive the RF energy signal). The adaption of the unitcells to allow leakage of the RF energy signal is a result of acapacitive inductance element (antenna) being placed in the near-fieldof one or more of the unit cells. This process continues to charge theelectronic device 104.

FIG. 2C is a flow diagram illustrating a more detailed process 260 ofthe illustrative charging surface in accordance with one or moreembodiments of the present disclosure. The process 260 may start at step262, where an RF energy signal may be provided at a charging surface.The RF energy signal may be an RF energy signal that is provided at thecharging surface by being contained (trapped/stored) or propagatedwithin a substrate of the charging surface. In an alternativeembodiment, rather than providing the RF energy signal at the chargingsurface, an RF signal that is used to cause the RF energy signal to bepropagated within the substrate may be turned off until a change incapacitance, inductance, or RF signal is sensed at the charging surfaceby a passive or active electronic device. Still yet, the RF energysignal may be intermittently turned on or turned on at a low power leveluntil an electronic device is determined to be proximately located oractually within the near-field of the charging surface.

At step 264, an RF antenna of an electronic device may enter anear-field of the charging surface. The near-field may be a range atwhich the charging surface is capable of leaking the RF energy signalfrom the surface in response to a capacitance and/or inductance changenear the charging surface, as further described herein.

At step 266, the RF energy signal may be leaked from the chargingsurface in response to the RF antenna entering the near-field of thecharging surface. As an example, if the amount of RF energy in the RFenergy signal that is distributed and being propagated within thesubstrate of the charging surface is 5 W, then the RF energy signal mayautomatically be routed to a location (e.g., above one or more unitcells) of the antenna of the electronic device that is within thenear-field of the charging surface and leaked therefrom to cause the 5 Wto be applied to the antenna. As understood in the art, the amount ofcharge that results from being in the near-field of the charging surfaceis based on the amount of coupling between the two antennas. If, forexample, a coupling ratio is 1, then there is 0 dB loss. If, forexample, the coupling ratio is 0.5, then there is a 3 dB loss.

At step 268, when the RF antenna exits from the near-field of thecharging surface, the RF energy signal stops being leaked from thecharging surface at step 270. At that time, the RF energy signal againis trapped/stored within the substrate of the charging surface.Alternatively, in one embodiment, the RF signal that is applied to thecharging surface to create the RF energy signal is turned off to savepower.

FIG. 3A illustrates a schematic diagram 300 of various componentscomprising an embodiment of the electronic device 104. The electronicdevice 104 may include a receiver component 302, one or more antennas304, a battery 312 that is to be charged in accordance with the presentdisclosure, and an optional communications component 310. In someembodiments, the communications component 310 may be included in thereceiver component 302. In some embodiments, the receiver component 302comprises circuitry including one or more switch elements 305, arectifier 306, and a power converter 308, where the rectifier 306 andpower converter 308 may be combined. The receiver 302 may be positionedwithin the electronic device 104 and connected to the electronic deviceantenna(s) 304, battery 312, and optional communications component 310.In some embodiments, the receiver component 302 may include a housingmade of any suitable material, for example plastic or hard rubber thatmay allow for signal or wave transmission and/or reception.

The device antennas 304 may include one or more antenna types capable ofoperating in frequency bands similar to the bands described above withrespect to FIG. 2A. In some embodiments, the device antennas 304 mayinclude an antenna designed for Wi-Fi data communication with theelectronic device 104, and an antenna designed for wireless datacommunication associated with telecommunications of the electronicdevice 104. The antennas 304 may be conventional and native to theelectronic device 104 as produced off-the-shelf for consumer usage. Insome embodiments, the device antennas 304 that operate in the frequencybands as described above serve at least two purposes. One exemplarypurpose is to facilitate the data communication with the electronicdevice 104 over wireless standards such as Bluetooth or WLAN forcommunication of user data as well as for communication of data relatedto the wireless charging function. A second purpose is to receive the RFcharging signal from a charging surface and provide this signal to thereceiver component 302. In such embodiments the device antennas 304 areserving two functions, and there is no separate dedicated antenna forreception of wireless charging signal.

However, in other embodiments, the electronic device 104 may include twosets of antennas. One set of one or more antennas to facilitate wirelessdata communication such as over Bluetooth or WLAN for communication ofuser data as well as data related to wireless charging operation; asecond set of one or more antennas to receive RF wireless chargingsignals and provide this signal to the receiver component 302. In thisembodiment, one set of antenna(s) is dedicated to the reception of RFcharging signal. Note that in this embodiment, use of separate set ofantenna(s) allows for the data communication and RF charging to operateon different frequencies if desired.

The charging surface has a certain operating frequency band. Dependingon that operating frequency band of an antenna of an electronic device104, the antenna of the electronic device 104 is to be within theoperating frequency band of the charging surface so that power transferwithin the near-field may be made. As an example, if the RF frequency ofthe RF energy signal operates within a Wi-Fi frequency band, thenantennas for mobile communications will not cause leakage of the RFenergy signal due to being outside the frequency band of the chargingsurface. In one embodiment, a separate device, such as a power pack withan antenna, power converter, and battery, may be configured to operateat a frequency outside the frequency band of conventional mobilecommunications (e.g., GSM, LTE, etc.). As an example, the chargingsurface may be configured to operate over an unlicensed frequency band,and a power pack may be configured to also operate over that frequencyband so that communications are not impacted when being charged by thecharging surface.

In some embodiments, the receiver component 302 may incorporate antennas(not shown) that are used in lieu of, or in addition to, the electronicdevice antennas 304. In such embodiments, suitable antenna types mayinclude patch antennas with heights from about 1/24 inch to about 1 inchand widths from about 1/24 inch to about 1 inch, or any other antenna,such as a dipole antenna, capable of receiving RF energy signalsgenerated by the charging surface 102. Alternative dimensions may beutilized, as well, depending on the frequencies being transmitted by theantenna. In any event, regardless of whether the original deviceantennas 304 or additional antennas incorporated into the receiver 302are used, the antennas should be tuned or otherwise be configured toreceive the RF energy signal generated by the charging surface 102 whenplaced within a near-field distance from the charging surface 102. Insome embodiments, the receiver component 302 may include circuitry forcausing an alert signal to indicate that the RF energy signal isreceived. The alert signal may include, for example, a visual, audio, orphysical indication. In an alternative embodiment, rather than using anantenna internal to an electronic device, a separate charging device,such as a “back pack” that may simultaneously operate as a protectivecase, as an example, for the electronic device (e.g., mobile phone), mayinclude an antenna along with a power conversion electronic device thatconverts the RF energy signal into a DC power signal.

The switch element(s) 305 may be capable of detecting the RF energysignals received at one or more of the antennas 304, and directing thesignals to the rectifier 306 when the detected signals correspond to apower level that exceeds a threshold. The switch element(s) may beformed from electronics, such as diode(s), transistor(s), or otherelectronic devices that may be used to determine a power level, absoluteor average, that causes the switch element(s) 305 to route the signalfrom a receiver to the rectifier 306 for power conversion thereby. Forexample, in some embodiments, the switch may direct the received RFenergy signals to the rectifier 306 when the RF energy signal receivedat the antenna 304 is indicative of a wireless power transfer greaterthan 10 mW. In other embodiments, the switch may direct the received RFenergy signals when they are indicative of a wireless power transfergreater than 25 mW. This switching acts to protect from damagingelectronic components, such as a receiver circuit, of the electronicdevice 104 by preventing a power surge from being applied thereto. Ifthe threshold power is not reached, the electronic device operates in aconventional manner.

The rectifier 306 may include diodes, resistors, inductors, and/orcapacitors to rectify alternating current (AC) voltage generated byantennas 304 to direct current (DC) voltage, as understood in the art.In some embodiments, the rectifier 306 and switch 305 may be placed asclose as is technically possible to the antenna element 304 to minimizelosses. After rectifying AC voltage, DC voltage may be regulated and/orconditioned using power converter 308. Power converter 308 can be aDC-DC converter, which may help provide a constant voltage output,regardless of input, to an electronic device or, as in this embodiment,to a battery 312. Typical voltage outputs can be from about 0.5 volts toabout 10 volts. Other voltage output levels may be utilized, as well.

Optional communications component 310, similar to that described abovewith respect to FIG. 2A, may be included in electronic device 104 tocommunicate with the communications component 210 and other electronicequipment. The communications component 310 may be integrated with thereceiver component 302 or may be a discrete component located in theelectronic device 104. In some embodiments, the communications component310 may be based on standard wireless communication protocols, which mayinclude Bluetooth® or ZigBee®. In addition, communications component 310may be used to communicate other data, such as an identifier for theelectronic device 104 or charging surface 102, battery level, location,power requirements specific to the electronic device 104, or other data.

FIG. 3B is a flow diagram 350 illustrating general operation of theelectronic device 104 in accordance with one or more embodiments of thepresent disclosure. At step 352, the antenna 304 receives an RF energysignal from one or more of the unit cells of the charging surface 102when the antenna 304 is tuned to the frequency of the RF energy signal(or is otherwise configured to receive the RF energy signal) and ispositioned within a near-field distance from one or more of the antennas204 of the unit cells. At step 354, the receiver component 302 convertsthe received RF energy signal to a power signal that is used to chargethe device battery 312 at step 356. Alternatively, rather than charginga battery, the power signal may power circuitry of the electronic devicedirectly, thereby enabling the electronic device to be operatedindependently of a battery.

FIG. 4A illustrates a schematic diagram of an electrical circuit model400 a representing the electrical state of the charging surface 102 whenthe electronic device 104 is not positioned within the near-fielddistance from the charging surface 102. The electrical circuit model 400a includes circuitry 402 representative of the electromagnetic operationof the charging surface 102 when no electronic device antenna 304 ispositioned in a near-field distance from the charging surface 102. Theelectrical circuit model 400 a represents a model of the chargingsurface 102 that is configured not to leak or otherwise output RFsignals due to not being tuned or otherwise operating as high-impedanceprior without an antenna of an electronic device being positioned withinthe near-field distance of the charging surface 102.

FIG. 4B illustrates a schematic diagram of an electrical circuit model400 b representing an electrical connection between the charging surface102 and the electronic device 104 when the electronic device 104 ispositioned within the near-field distance from the charging surface 102and the antenna(s) 304 of the electronic device 104 is tuned to thecenter frequency of the RF energy signal generated by the chargingsurface 102. The electrical circuit model includes circuitry 404representative of the electronic device 104 being electromagneticallycoupled to the circuitry 402 of the charging surface 102 to cause achange in the electromagnetic operation of the charging surface 102. Theelectrical circuit model 400 b represents a model of the chargingsurface 102 that is configured to leak or otherwise output RF signalswhen an antenna of an electronic device is positioned within thenear-field distance of the charging surface 102 so as to cause therepresentative electrical circuit model 400 b to become tuned due tocoupling effects, as understood in the art and further described withregard to FIGS. 4C and 4D.

FIG. 4C shows schematic models of equivalent circuits with two states ofenergy flow without and with an electronic device positioned in anear-field distance of the charging surface. In the first state, aircauses a reflection of energy from a high impedance surface of thecharging surface. In the second state, inclusion of an antenna receiverin a near-field of the surface forms an inductive coupling that enablesenergy flow through the high impedance surface of the charging surface.FIG. 4D is an illustration of an alternative representation of theschematic models of FIG. 4C. It should be understood that the models inFIGS. 4C and 4D are simplified and more complex models may be utilizedto represent the adaptive high-impedance surface.

Referring now to FIGS. 5A-5D, an example embodiment of an antennaportion 500 of a charging surface is provided, wherein the antennaportion 500 includes a plurality of unit cells 502 arranged in a matrixformation. Each of the unit cells 502 includes two substrate layers 515a and 515 b. The top substrate layer 515 a of each of the unit cells 502includes a metal portion 504 (e.g., copper) defining apertures 506positioned at the top of the unit cells 502. The bottom substrate layer515 b of each unit cell 502 includes a patch antenna 510 comprising ametal patch 512 having an electrical connection through a via 508 to aground plane 514. The ground plane 514 may be a metamaterial. The groundplane 514 is connected to an RF port 505 as shown in FIG. 5B forconducting RF signals to unit cells 502.

In some embodiments, the patch antenna 510 is configured to generate theRF energy signal that radiates within the top substrate layer 515 a. Inaccordance with the present disclosure, the RF energy signal remains inthe top substrate layer 515 a until the RF energy signal decays or isleaked to an antenna 304 (FIG. 3) of an electronic device positioned ona charging surface.

In some embodiments, the size of the aperture 506 is determined inaccordance with the periodic frequency of the RF energy signal such thatthe RF energy signal does not leak from the aperture 506 in the unitcells 502 unless an antenna tuned to the frequency of the RF energysignal is positioned in a near-field distance (e.g., less than about 4mm) from at least one of the unit cells 502.

Referring now to FIGS. 6A-6D, an example embodiment of an antennaportion 600 of a charging surface is provided, where the antenna portion600 is composed of a plurality of unit cells 602 arranged in a matrixformation. Each of the unit cells 602 includes one substrate layer 615having a metal portion 604 (e.g., copper) defining an aperture 606positioned at the top of the unit cells 602. The unit cells 602 alsoinclude a patch antenna 610 formed by a metal patch 612 having anelectrical connection through a via 608 to a ground plane 614. Theground plane 614 may be physically and electrically connected to an RFport 605, as shown in FIG. 6B. The RF port 605 may be used to provide anRF energy signal from an RF energy signal generator to be applied toeach of the unit cells 602, and the ground plane 614 may be electricallyconnected to a ground portion of the RF port 605.

In the embodiment illustrated in FIGS. 6A-6D, the patch antenna 610 ispositioned within the unit cell 602 such that the aperture 606 is formedaround a perimeter of the metal patch 612. In some embodiments, thepatch antenna 610 is configured to propagate the RF energy signal fromthe top surface of the substrate layer 615. In accordance with thepresent disclosure, the RF energy signal remains at or near the topsurface of the substrate layer 615 until the RF energy signal decays oris received by the electronic device antenna 304.

In some embodiments, the size of the aperture 606 is determined inaccordance with the periodic frequency of the RF energy signal generatedby the patch antenna 610 such that the RF energy signal does not or hasminimal leakage from the aperture 606 of the unit cells 602 unless anantenna tuned to the frequency of the RF energy signal is positioned ina near-field distance from at least one of the unit cells 602. Theaperture 606 may be altered in dimension depending on frequency of theRF energy signal so as to be properly tuned for preventing leakage ofthe RF energy signal when no electronic device is positioned in thenear-field. It should be understood that a number of layers of the unitcell may vary depending on the application, where different number oflayers may provide different responses from the unit cells to providedifferent harmonic responses (e.g., higher or shifted harmonicfrequencies for different wireless powering applications).

FIG. 6E is an illustration of a cross-sectional view of an illustrativecharging surface 620 inclusive of a plurality of unit cells 622 a-622 n(collectively 622). The unit cells 622 include vias 624, patches orslots 626, substrate 628, and surface element 630. The surface element630 include a plurality of holes or patches 632 a-632 n (collectively632). In one embodiment, the length and width of the unit cells 622 arebetween about 5 mm and about 10 mm. It should be understood thatalternative dimensions may be utilized as a function of the frequencybeing propagated or trapped/stored by the unit cells and/or the materialbeing used to form the surface 622. The substrate 628 may be formed ofRogers FR-4, ceramic, or other material. The use of a substrate 628,such as ceramic, allows for the dimensions of the unit cells to besmaller than otherwise possible without a substrate 628.

Resonance

A resonant coupler may be formed when a device to be charged itselfenables transmission of power and operates as part of a charging system.For example, a mobile telephone having a metallic case may be utilizedto complete a charging device, as further described in FIGS. 7A and8A-8C. The charging system may work in two different stages. A firststage may provide for a field being fed through a feeding point (e.g.,slot on a ground plane) into a first cavity and getting trapped in thestructure of the first cavity. The first cavity may include a number oftouch/leak points that are activated when being touched by orproximately close to an electronic device with a metal case. A secondstage may operate when the electronic device is placed on the surface ata touch point so that energy leaks out of the second cavity formed inpart by the electronic device on top of the charging surface.

FIGS. 7A, 8A-8C illustrate a cross-sectional view of the electronicdevice 104 positioned a distance D within a near-field distance D_(NF)from a charging surface 700, in accordance with an embodiment of thepresent disclosure. Thus, in accordance with the present embodiment, theantenna(s) 304 of the electronic device 104 are positioned a distance D,which is within the near-field distance D_(NF). The RF energy signalsgenerated by the charging surface 700 in the near-field do not achieve aparticular polarization before being received by the antenna(s) 304 ofthe electronic device 104. In some embodiments, the near-field distanceD_(NF) is less than approximately 4 mm.

In the embodiment illustrated in FIGS. 7A and 8A-8C, the electronicdevice 104 includes a back surface 701 that is generally formed ofmetallic surfaces 702 a, 702 b, and 702 c and includes defining gaps 704a and 704 b that are non-metallic and that may be formed of a plastic,glass, or any other material suitable to allow signal or wavetransmission and/or reception. The gaps 704 a and 704 b are locatedproximate the antennas 304 such that the antennas 304 may receivesignals entering through the gaps 704 a and 704 b. The metallic surfaces702 a, 702 b, and 702 c reflect RF energy signals 802, as shown in FIG.8A, such that the RF energy signal 802 generated by the charging surface102 traverses or resonates within a cavity 706 formed between a topsurface 708 of the charging surface 700 and one or more of the metallicsurfaces 702 a, 702 b, and 702 c until it reaches at least one of thegaps 704 a and 704 b. The RF energy signal 802 traverses or resonatesbetween the metal surface 702 b, for example, and top surface of thecharging surface 700 as a trapped wave in the cavity 706 (see FIG. 8A,RF energy signal 802 reflecting between the two surfaces). The gaps 704a and 704 b are positioned above the charging surface 700, and morespecifically, one or more unit cells of the charging surface 700, sothat the RF energy signal 802 can traverse the cavity 706 to reach oneof the gaps 704 a and 704 b. When the RF energy signal 802 reaches thegap 704 a, the RF energy signal 802 enters through the gap 704 a and isreceived by the device antenna 304.

More particularly, as shown in FIGS. 8B and 8C, the charging surface 700is shown to include a cover 802 within which a first cavity 804 a and asecond cavity 804 b (collectively 804) are formed by a ground plane 806that separates the two cavities 804. The ground plane may be formed ofmetamaterial, as described herein. The charging surface 700 may alsoinclude one or more touch points 810 from which an RF energy signalemanates. In operation, a first stage may provide for an RF energysignal being fed through a feeding point (e.g., slot on a ground plane)into the first cavity 804 a and gets trapped in the structure of thefirst cavity 804 a. The first cavity 804 a may include a number oftouch/leak points 810 that are activated when being touched by orproximately close to an electronic device with a metal case. A secondstage may operate when the electronic device is placed on the cover 802at least one of the touch points 810 so that energy leaks out of thesecond cavity 804 b formed in part by the electronic device on top ofthe cover 802 of the charging surface 700. Because only a few touchpoints 810 are utilized in this charging surface 700, fewer poweramplifiers are needed to supply RF energy signals, thereby costing lessthan having many more touch points. In one embodiment, four touch points810 may be utilized. However, it should be understood that the number oftouch points may vary depending on the size of the area provided by thecharging surface 700. If a large area (e.g., desk) is provided, thenmore touch points 810 are provided. If a smaller area (e.g., pad) isprovided, then fewer touch points 810 are provided.

In some embodiments, such as that shown in FIGS. 7A and 8A, the metallicsurfaces 702 a, 702 b, and 702 c are positioned substantially parallelto the top surface 708 of the charging surface 700. Although the RFenergy signal 802 is represented in FIG. 8A as having a trianglewaveform reflection, it should be appreciated that the RF energy signal802 may be reflected in other patterns, as understood in the art. Asused herein, “traverses” refers to the RF energy signal travelling alongor through a space or cavity by reflecting off of surfaces.

FIG. 8D shows the electronic device 104 being placed on the chargingsurface 700. As the electronic is placed on the charging surface 700,energy flow 812 from an RF energy signal is created in the cavity formedby the electronic device 104 and the charging surface.

FIG. 7B illustrates an illustrative electronic schematic of theelectronic device 104 of FIG. 7A. The electronic device 104 is shown toinclude the two gaps 704 within which the antennas 304 are positioned toreceive RF signals 706. The antennas 304 are in electrical communicationwith an RF integrated circuit (RF-IC) 708 via electrical conductor 710.The RF-IC 708 is shown to include a switch 712 and rectifier device 714.The switch 712 may be configured to cause the RF signals 706 to berouted to a transceiver (XCVR) 716 when communications signals. Thetransceiver 716 is a conventional transceiver used for usercommunications, as understood in the art. However, in response to the RFsignals 706 crossing a certain threshold level, such as 0.1 W or 0.25 W,the switch 712 may be activated to cause the RF signals 706 to be routedto the rectifier device 714 that includes one or more rectifiers 718therein. The switch 712 may be a solid state switch, as understood inthe art. An output from the rectifier device 714 may be routed to abattery 720 used to power the electronic device 104.

Referring now to FIG. 9, an example method is shown in flow diagram 900for charging the electronic device 104 with the charging surface 102 inaccordance with an embodiment of the present disclosure. In theembodiment illustrated in FIG. 9, the charging surface 102 communicateswith the electronic device 104 via respective communication components210 and 310. At step 902, the charging surface communication component210 receives, from the electronic device communication component 310, asignal indicative of a request to charge the electronic device 104. Insome embodiments, this signal may include, for example, anidentification of the electronic device 104, a battery level, powerrequirements of the electronic device 104, or other information. Forexample, in some instances, the electronic device 104 may be a devicehaving a lower power requirement, such as, for example, a smart-watch orother wearable technology. In order to avoid receiving a large powersurge that would damage the smart-watch, the charge request couldinclude a power limit, such as, 0.5 W. Alternative power levels may beutilized, as well. Similarly, the electronic device 104 may have alarger power requirement. In such cases, the charge request couldinclude the larger power requirement, such as 5 W, for charging theelectronic device 104.

Rather than receiving an active charge request, the charging surface mayreceive or sense any wireless or radiation signal from an electronicdevice that indicates that an electronic device is proximate to thecharging surface, including but not limited to the presence or absenceof reflection of an RF energy signal transmitted by the chargingsurface. Any receiver or sensor may be utilized to sense such a signalfrom an electronic device. In an alternative embodiment, a proximityswitch or pressure switch may be utilized to detect that an electronicdevice is proximate to or positioned on the charging surface. Still yet,a magnetic switch or light switch may be utilized.

At step 904, the microcontroller 208 initiates generation of an RFenergy signal in accordance with the data provided in the chargerequest. For example, if the charge request indicates the powerrequirements of the electronic device 104, then the microcontroller 208causes the RF energy signal to be generated such that the powertransmitted to the electronic device 104 complies with the powerrequirements communicated in the charge request. In accordance with theabove example of a smart-watch, the microcontroller 208 may cause thecharging surface 102 to generate an RF energy signal capable ofproviding wireless power transfer of 0.5 W to the smart-watch. In oneembodiment, if an electronic device is sensed, then an RF energy signalmay be generated.

As discussed herein, the RF energy signal is generated in the unit cellsof the charging surface 102, and substantially remains in the unit cellsuntil the RF energy signal decays or is leaked. When an antenna 304tuned to the frequency of the RF energy signal is placed within anear-field distance from one or more of the unit cells, those unitcell(s) allow the RF energy signal to leak to the antenna 304 at step906.

As step 908, the leaked RF energy signal is received at the antenna(s)304 tuned to the frequency of the RF energy signal and placed within thenear-field distance from the unit cell(s).

At step 910, the received RF energy signal is converted to a powersignal to charge the battery 312 of the electronic device 104. This stepmay include detecting the RF energy signal received at the antenna 304,activating the switch mechanism 305 when the RF energy signal isindicative of a power signal greater than the threshold value (e.g., 10mW) rectifying the signal via the rectifier 306, and converting therectified signal to a DC power signal via the converter 308. The powersignal is then used to charge or operate the electronic device battery312 at step 912.

Although it is not illustrated in the flow diagram 900, thecommunications component 310 may, in some embodiments, transmit a signalto the charging surface 102 to request that the charging be suspended ordiscontinued. This may happen, for example, if the battery 312 of theelectronic device 104 is completely charged or reaches a desired chargelevel, the electronic device 104 is being turned off, the communicationscomponent 310 is being turned off or moved out of communication rangewith the communications component 210, or for other reasons. In anotherembodiment, in the event that the electronic device is no longer beingsensed, electronically, physically or otherwise depending on the sensorbeing utilized, then the communications component 210 may be turned off.

Referring now to FIG. 10, an example method is shown in flow diagram1000 for sensing the presence of and charging the electronic device 104with the charging surface 102 in accordance with an embodiment of thepresent disclosure. In the embodiment illustrated in FIG. 10, theelectronic device 104 does not communicate with the charging surface 102via respective communication components 210 and 310. This embodiment isrepresentative of instances where the electronic device 104 is turnedoff, has a drained battery, or is otherwise unable to communicate withthe charging surface 102. Thus, in the present embodiment, the chargingsurface 102 operates in a manner so as to avoid flooding an undetectedelectronic device 104 with excessive power. This is the manner that areceiver with a dead battery, and hence no ability to communicate withthe transmitter, may be charged.

At step 1002, the charging surface 102 generates a low-power RF energysignal, which is an RF energy signal capable of providing wireless,low-power transmission to an electronic device 104. Specifically, themicrocontroller 208 initiates generation of the low-power RF energysignal such that the power capable of being transmitted via thelow-power RF energy signal is “low-power.” For example, in someembodiments, low-power is 1 W. Alternative power levels may be utilized,as well. In some embodiments, detecting that an electronic device ispositioned within a near-field distance of the charging surface may beaccomplished by activating the unit cell patch antennas 204 with a 1%duty cycle.

In accordance with the present disclosure, the low-power RF energysignal is generated in the unit cells of the charging surface 102, andremains in the unit cells until the low-power RF energy signal decays oris leaked. When an antenna 304 tuned to the frequency of the low-powerRF energy signal is placed within a near-field distance from one or moreof the unit cells, those unit cells allow the RF energy signal to leakto the antenna 304 at step 1004.

At step 1006, the microcontroller 208 may sense the low-power RF energysignal present in the unit cells. For example, in some embodiments, themicrocontroller 208 may include sensing circuitry, such as, an RFcoupler capable of detecting a “reflection” of the low-power RF energysignal, where the reflection is representative of, for example,approximately 10% of the low-power RF energy signal present in the unitcells. The microcontroller 208 may, therefore, calculate the low-powerRF energy signal present in the unit cells based on the reflected valuesensed by the microcontroller 208. Although the sensing performed atstep 1006 is illustrated in a sequential order in FIG. 10, it should beappreciated that this step may be performed in any order or repeatedcontinuously in parallel with the processes performed in the flowdiagram 1000. The low-power RF energy signal may be generatedperiodically or aperiodically in a pulsed or other manner to determineif an electronic device is present, as indicated in the diagram 1000.

Once the microcontroller 208 senses the low-power RF energy signalpresent in the unit cells, the sensed low-power RF energy is compared toa threshold value at step 1008 to determine whether to generate asubsequent low-power RF energy signal within the unit cells. Instancesin which the sensed low-power RF energy signal is less than thethreshold value are indicative of a situation in which the low-power RFenergy signal has either decayed or leaked to an antenna tuned to thefrequency of the low-power RF energy signal and positioned within anear-field distance from one or more of the unit cells. Thus, if thesensed low-power RF energy signal is less than the threshold, it ispresumed the low-power RF energy signal has either leaked or decayed, sothe process returns to step 1002 and the microcontroller 208 activatesthe antennas 204 to generate a subsequent low-power RF energy signal.Otherwise, when the reflection is above the threshold, the low-power RFenergy signal remains in the substrate and subsequent RF signals are notgenerated so that the unit cells of the charging surface 102 do notcontinue to build up energy. Accordingly, the process returns to step1006, and the microcontroller 208 continues to sense the low-power RFenergy signal present in the unit cells.

The method illustrated in FIG. 10 is indicative of a situation m whichno communication component 310 is communicating with the chargingsurface 102. For example, the battery 312 of the electronic device 104may be too depleted to activate the communication component 310.However, once the battery 312 has sufficient charge, the electronicdevice 104 may, in some embodiments, activate the communicationcomponent 310. At that time, the communication component 310 mayinitiate communication with the communication component 210 of thecharging surface 102, and the charging surface 102 may switch(illustrated at step 1010, FIG. 10) to the charging method illustratedin FIG. 9 and described above.

Harmonic Filter

In conventional power-transmission systems, various electronic elementsthat form the system are often lumped together, and losses experiencedby each lumped element are compounded such that the system, as a whole,experiences a larger loss than each of the elements individually. Forexample, if a system has an antenna that is 90% efficient lumped with anamplifier that is 90% efficient, then the combined efficiency of asystem comprising these two elements is approximately 81%. As moreelements are added, the overall efficiency of the system is furtherreduced. Accordingly, in order to increase the efficiency of thedisclosed charging surface, some embodiments of the charging surface mayinclude filter elements such as, a harmonic filter, to reduce theradiated energy in frequencies other than the intended wireless chargingsignal, and specifically to reduce the energy in the harmonics of theintended wireless charging signal. A harmonic filter may, for example,attenuate these frequency components by 40 dB to 70 dB

FIGS. 11A and 11B illustrate perspective and cross-sectional views,respectively, of a representative unit cell 1102 comprising anembodiment of the charging surface 102, where each unit cell 1102 has aharmonic filter element 1104 positioned on a top surface of the unitcell 1102. The unit cell 1102 illustrated in FIGS. 11A and 11B issimilar to that described above and shown in FIGS. 6A-6D, however, theharmonic filter element 1104 may be placed on a top surface of unitcells of a different embodiment, such as the embodiment described aboveand illustrated in FIGS. 5A-5D.

It should be appreciated that the harmonic filter element 1104 includedin each unit cell 1102 may be a discrete filter element, or it may be aportion of a larger, single harmonic filter element spanning the topsurfaces of multiple unit cells 1102 forming the charging surface 102.Thus, the charging surface 102 includes, in such embodiments, a harmonicfilter element 1104 placed over the unit cells 1102 such that thecharging surface 102 includes a harmonic filter positioned over a matrix(or array) of transmit antennas (e.g., patch antennas 610).

In the embodiment illustrated in FIGS. 11A and 11B, each of the unitcells 1102 includes a single substrate layer 615, and the harmonicfilter element 1104 present in each of the unit cells 1102 comprises asingle harmonic filter element spanning the entire top surface area ofthe unit cells 1102. In other embodiments, however, the harmonic filterelement 1104 may include multiple harmonic filter elements, where one ofthe multiple harmonic filter elements are disposed on a top surface ofone of the elements forming the unit cells 1102. It should be understoodthat the unit cell with the harmonic rejection filter may be formed by amore complex unit cell, such as a unit cell that includes more layersand features within the unit cell. For example, this latter embodimentcould be represented by a harmonic filter element 1104 placed on the topsurface area of the patch antenna 610, a harmonic filter element 1104placed on the top surface area of the metal portion 604, and no harmonicfilter element covering the aperture 606.

In some embodiments, the harmonic filter element 1104 is formed of twoor more screen layers, wherein each layer includes a screen to filterout specific harmonics of the intended wireless charging signal. Theharmonic filter 1104 acts to filter the RF energy signal generated bythe patch antenna 610 such that the RF energy signal operates at aparticular frequency (also referred to herein as a center frequency). Asa result of the harmonic filter element 1104 being a passive mechanicaldevice, loss in signal power is reduced as compared with an electronicfilter.

FIGS. 12A and 12B illustrate perspective and cross-sectional views,respectively, of a representative unit cell 1202 comprising anembodiment of the charging surface 102, where each unit cell 1202 has aharmonic filter element 1204 positioned within a top substrate layer 515a of the unit cell 1202 (or optionally between the top substrate layer515 a and a bottom substrate layer 515 b). It should be appreciated thatthe harmonic filter element 1204 included in each unit cell 1202 may bea discrete filter element, or it may be a portion of a larger, singleharmonic filter element spanning the top substrate layers 515 a ofmultiple unit cells 1202 forming the charging surface 102. Thus, thecharging surface 102 includes, in such embodiments, a harmonic filterelement 1204 placed within the top substrate layers 515 a of the unitcells 1202 such that the charging surface 102 includes a harmonic filterpositioned over a matrix (or array) of transmit antennas (e.g., patchantennas 510).

In the embodiment illustrated in FIGS. 12A and 12B, the unit cells 1202include a top substrate layer 515 a and a bottom substrate layer 515 b,and the harmonic filter element 1204 present in the top substrate layer515 a of each of the unit cells 1202 comprises a single harmonic filterelement spanning the entire area of the top substrate layer 515 a of theunit cells 1202. In other embodiments, however, the harmonic filterelement 1204 may span only a portion of the top substrate layer 515 asuch that the harmonic filter element 1204 is disposed above only thepatch antenna 510, which is located in the bottom substrate layer 515 b.

In some embodiments, the harmonic filter element 1204 is formed of twoor more screen layers, wherein each layer includes a screen to filterout specific harmonics of the intended wireless charging signal. Theharmonic filter 1204 acts to filter the RF energy signal generated bythe patch antenna 510 such that the RF energy signal operates at aparticular frequency (also referred to herein as a center frequency). Asa result of the harmonic filter element 1204 being a passive mechanicaldevice, loss in signal power is reduced as compared with an electronicfilter.

The foregoing method descriptions and flow diagrams are provided merelyas illustrative examples and are not intended to require or imply thatthe steps of the various embodiments must be performed in the orderpresented. The steps in the foregoing embodiments may be performed inany order. Words such as “then,” “next,” etc., are not intended to limitthe order of the steps; these words are simply used to guide the readerthrough the description of the methods. Although process flow diagramsmay describe the operations as a sequential process, many of theoperations can be performed in parallel or concurrently. In addition,the order of the operations may be rearranged. A process may correspondto a method, a function, a procedure, a subroutine, a subprogram, etc.When a process corresponds to a function, its termination may correspondto a return of the function to the calling function or the mainfunction.

The various illustrative logical blocks, modules, circuits, andalgorithm steps described in connection with the embodiments disclosedherein may be implemented as electronic hardware, computer software, orcombinations of both. To clearly illustrate this interchangeability ofhardware and software, various illustrative components, blocks, modules,circuits, and steps have been described above generally in terms oftheir functionality. Whether such functionality is implemented ashardware or software depends upon the particular application and designconstraints imposed on the overall system. Skilled artisans mayimplement the described functionality in varying ways for eachparticular application, but such implementation decisions should not beinterpreted as causing a departure from the scope of the presentinvention.

Embodiments implemented in computer software may be implemented insoftware, firmware, middleware, microcode, hardware descriptionlanguages, or the like, or any combination thereof. A code segment ormachine-executable instructions may represent a procedure, a function, asubprogram, a program, a routine, a subroutine, a module, a softwarepackage, a class, or any combination of instructions, data structures,or program statements. A code segment may be coupled to another codesegment or a hardware circuit by passing and/or receiving information,data, arguments, parameters, or memory contents. Information, arguments,parameters, data, etc. may be passed, forwarded, or transmitted via anysuitable means including memory sharing, message passing, token passing,network transmission, etc.

The actual software code or specialized control hardware used toimplement these systems and methods is not limiting of the invention.Thus, the operation and behavior of the systems and methods weredescribed without reference to the specific software code beingunderstood that software and control hardware can be designed toimplement the systems and methods based on the description herein.

When implemented in software, the functions may be stored as one or moreinstructions or code on a non-transitory computer-readable orprocessor-readable storage medium. The steps of a method or algorithmdisclosed herein may be embodied in a processor-executable softwaremodule which may reside on a computer-readable or processor-readablestorage medium. A non-transitory computer-readable or processor-readablemedia includes both computer storage media and tangible storage mediathat facilitate transfer of a computer program from one place toanother. A non-transitory, processor-readable storage media may be anyavailable media that may be accessed by a computer. By way of example,and not limitation, such non-transitory, processor-readable media maycomprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage,magnetic disk storage or other magnetic storage devices, or any othertangible storage medium that may be used to store desired program codein the form of instructions or data structures and that may be accessedby a computer or processor. Disk and disc, as used herein, includecompact disc (CD), laser disc, optical disc, digital versatile disc(DVD), floppy disk, and Blu-ray disc where disks usually reproduce datamagnetically, while discs reproduce data optically with lasers.Combinations of the above should also be included within the scope ofcomputer-readable media. Additionally, the operations of a method oralgorithm may reside as one or any combination or set of codes and/orinstructions on a non-transitory, processor-readable medium and/orcomputer-readable medium, which may be incorporated into a computerprogram product.

The preceding description of the disclosed embodiments is provided toenable any person skilled in the art to make or use the presentinvention. Various modifications to these embodiments will be readilyapparent to those skilled in the art, and the generic principles definedherein may be applied to other embodiments without departing from thespirit or scope of the invention. Thus, the present invention is notintended to be limited to the embodiments shown herein but is to beaccorded the widest scope consistent with the following claims and theprinciples and novel features disclosed herein.

While various aspects and embodiments have been disclosed, other aspectsand embodiments are contemplated. The various aspects and embodimentsdisclosed are for purposes of illustration and are not intended to belimiting, with the true scope and spirit being indicated by thefollowing claims.

What is claimed is:
 1. A method of wirelessly delivering power to areceiver device, the method comprising: while a receiver device lackssufficient power to send an electromagnetic communication signal:radiating, via an antenna of a unit cell included in a near-fieldcharging pad, a radio frequency (RF) power transmission wave at a firstpower level, wherein the near-field charging pad includes a plurality ofunit cells, including the unit cell; detecting, by the near-fieldcharging pad, an amount of energy associated with the RF powertransmission wave that is reflected by one or more of the plurality ofunit cells; determining, by the near-field charging pad, that thereceiver device is within a near-field charging distance of thenear-field charging pad when the amount satisfies a threshold; and inresponse to determining that the receiver device is within thenear-field charging distance of the near-field charging pad, continuingto radiate, via the antenna of the unit cell, the RF power transmissionwave at the first power level; and upon receiving an electromagneticcommunication signal generated by the receiver device: ceasing toradiate the RF power transmission wave at the first power level; andradiating, via the antenna of the unit cell, a new RF power transmissionwave at a second power level greater than the first power level.
 2. Themethod of claim 1, wherein radiating the RF power transmission wave atthe first power level occurs before detecting any receiver deviceswithin the near-field distance of the near-field charging pad.
 3. Themethod of claim 1, wherein: the electromagnetic communication signalincludes device-specific characteristics of the receiver device, and thesecond power level of the new RF power transmission wave radiated by theantenna of the unit cell is determined based at least in part on thedevice-specific characteristics of the receiver device.
 4. The method ofclaim 3, wherein the device-specific characteristics include one or moreof: an identifier of the receiver device, a battery level of thereceiver device, and a power requirement of the receiver device.
 5. Themethod of claim 1, wherein: the near-field charging pad includes acommunications radio for receiving the electromagnetic communicationsignal from the receiver device; and the receiver device includes acorresponding communications radio for sending the electromagneticcommunications signal to the near-field charging pad.
 6. The method ofclaim 1, wherein each unit cell in the plurality of unit cells radiates,via a respective antenna, a respective RF power transmission wave at thefirst power level.
 7. The method of claim 6, wherein the detecting ofthe amount of energy associated with the RF power transmission wave isperformed in conjunction with detecting a respective amount of energyassociated with each of the RF power transmission waves that isreflected by the plurality of unit cells of the near-field charging pad.8. The method of claim 1, wherein: the near-field charging pad includesa controller and an RF coupler; the controller is connected with the RFcoupler; and the RF coupler (i) detects the amount of energy associatedwith the RF power transmission wave that is reflected by the one or moreunit cells of the plurality of unit cells and (ii) provides the amountto the controller.
 9. The method of claim 1, wherein the receiver deviceincludes: a wireless power receiver for receiving RF power transmissionwaves; and an electronic device coupled with the wireless powerreceiver.
 10. A near-field charging pad for wirelessly delivering powerto a receiver device, the near-field charging pad comprising: while areceiver device lacks sufficient power to send an electromagneticcommunication signal: radiating, via an antenna of a unit cell includedin a near-field charging pad, a radio frequency (RF) power transmissionwave at a first power level, wherein the near-field charging padincludes a plurality of unit cells, including the unit cell; detecting,by the near-field charging pad, an amount of energy associated with theRF power transmission wave that is reflected by one or more of theplurality of unit cells; determining, by the near-field charging pad,that the receiver device is within a near-field charging distance of thenear-field charging pad when the amount satisfies a threshold; and inresponse to determining that the receiver device is within thenear-field charging distance of the near-field charging pad, continuingto radiate, via the antenna of the unit cell, the RF power transmissionwave at the first power level; and upon receiving an electromagneticcommunication signal generated by the receiver device: ceasing toradiate the RF power transmission wave at the first power level; andradiating, via the antenna of the unit cell, a new RF power transmissionwave at a second power level greater than the first power level.
 11. Thenear-field charging pad of claim 10, wherein radiating the RF powertransmission wave at the first power level occurs before detecting anyreceiver devices within the near-field distance of the near-fieldcharging pad.
 12. The near-field charging pad of claim 10, wherein: theelectromagnetic communication signal includes device-specificcharacteristics of the receiver device, and the controller is furtherconfigured to determine the second power level of the new RF powertransmission wave based at least in part on the device-specificcharacteristics of the receiver device.
 13. The near-field charging padof claim 12, wherein the device-specific characteristics include one ormore of: an identifier of the receiver device, a battery level of thereceiver device, and a power requirement of the receiver device.
 14. Thenear-field charging pad of claim 10, wherein: the near-field chargingpad includes a communications radio for receiving the electromagneticcommunication signal from the receiver device; and the receiver deviceincludes a corresponding communications radio for sending theelectromagnetic communications signal to the near-field charging pad.15. The near-field charging pad of claim 10, wherein each unit cell inthe plurality of unit cells radiates, via a respective antenna, arespective RF power transmission wave with the at the first power level.16. The near-field charging pad of claim 15, wherein the detecting ofthe amount of energy associated with the RF power transmission wave isperformed in conjunction with detecting a respective amount of energyassociated with each of the RF power transmission waves that isreflected by the plurality of unit cells of the near-field charging pad.17. The near-field charging pad of claim 10, wherein: the controller isconnected with the RF coupler; and the RF coupler (i) detects the amountof energy associated with the RF power transmission wave that isreflected by the one or more unit cells of the plurality of unit cellsand (ii) provides the amount to the controller.
 18. The near-fieldcharging pad of claim 10, wherein the receiver device includes: awireless power receiver for receiving RF power transmission waves; andan electronic device coupled with the wireless power receiver.
 19. Anon-transitory computer-readable storage medium storing executableinstructions that, when executed by one or more processors that are incommunication with a near-field charging pad, cause the near-fieldcharging pad to: while a receiver device lacks sufficient power to sendan electromagnetic communication signal: radiating, via an antenna of aunit cell included in a near-field charging pad, a radio frequency (RF)power transmission wave at a first power level, wherein the near-fieldcharging pad includes a plurality of unit cells, including the unitcell; detecting, by the near-field charging pad, an amount of energyassociated with the RF power transmission wave that is reflected by oneor more of the plurality of unit cells; determining, by the near-fieldcharging pad, that the receiver device is within a near-field chargingdistance of the near-field charging pad when the amount satisfies athreshold; and in response to determining that the receiver device iswithin the near-field charging distance of the near-field charging pad,continuing to radiate, via the antenna of the unit cell, the RF powertransmission wave at the first power level; and upon receiving anelectromagnetic communication signal generated by the receiver device:ceasing to radiate the RF power transmission wave at the first powerlevel; and radiating, via the antenna of the unit cell, a new RF powertransmission wave at a second power level greater than the first powerlevel.
 20. The non-transitory computer-readable storage medium of claim19, wherein radiating the RF power transmission wave at the first powerlevel occurs before detecting any receiver devices within the near-fielddistance of the near-field charging pad.
 21. The non-transitorycomputer-readable storage medium of claim 19, wherein: theelectromagnetic communication signal includes device-specificcharacteristics of the receiver device, and the second power level ofthe new RF power transmission wave radiated by the antenna of the unitcell is determined based at least in part on the device-specificcharacteristics of the receiver device.
 22. The non-transitorycomputer-readable storage medium of claim 21, wherein thedevice-specific characteristics include one or more of: an identifier ofthe receiver device, a battery level of the receiver device, and a powerrequirement of the receiver device.
 23. The non-transitorycomputer-readable storage medium of claim 19, wherein: the near-fieldcharging pad includes a communications radio for receiving theelectromagnetic communication signal from the receiver device; and thereceiver device includes a corresponding communications radio forsending the electromagnetic communications signal to the near-fieldcharging pad.
 24. The non-transitory computer-readable storage medium ofclaim 19, wherein the receiver device includes: a wireless powerreceiver for receiving RF power transmission waves; and an electronicdevice coupled with the wireless power receiver.